JPH09320098A - Optical pickup apparatus and composite optical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup apparatus and a composite optical apparatus used for an optical pickup apparatus of this type which enables writing or reading of data to or from a plurality of kinds of optical disks in different formats. SOLUTION: The optical pickup apparatus is constituted by combining a couple of laser couplers LC1 and LC2 which are designed to conform to the optimum specifications for writing or reading of the optical disks of different formats. Or, a laser coupler is structured by integrating a couple of laser couplers LC1 and LC2 on the same photodiode IC and it is then used for the optical pickup apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device and a composite optical device, and is particularly suitable for use in an optical disc system.

[0002]

2. Description of the Related Art In recent years, with the diversification of optical disk systems, a laser light for writing or reading on an optical disk, a laser light from a semiconductor laser having an emission wavelength of 780 nm, and an emission wavelength of 635 nm (or 650 n
There is an increasing number of incompatible optical discs of different formats that use laser light emitted from a semiconductor laser emitting red light in the m) band, laser light emitted from a semiconductor laser emitting blue light, etc. (for example, CD, CDR, MD, MMCD, DVD). Such).

When recording / reproducing a plurality of types of optical discs having different formats by the same optical disc system, a dedicated optical pickup device is required for each optical disc having a different format. On the other hand, since there is a large difference in the purpose and characteristics between the semiconductor laser for writing and the semiconductor laser for reading, it is easier to use the semiconductor laser only for writing and the semiconductor laser only for reading because the optical pickup device is easier to use. May be configured to.

[0004]

However, preparing an optical pickup device for each optical disc having a different format as described above leads to an increase in the size and cost of the optical disc system. Further, when an optical pickup device is configured by using a packaged write-only semiconductor laser and a read-only semiconductor laser, respectively, the optical pickup device becomes large in size, which in turn causes an increase in size of the optical disc system. It is difficult to adjust the optical axis of semiconductor lasers and photodetectors, etc., and assembly is difficult.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical pickup device capable of writing or reading on a plurality of types of optical discs having different formats, and being compact and easy to assemble. Another object of the present invention is to, when used in an optical pickup device, be capable of writing to or reading from a plurality of types of optical discs having different formats, and further, downsizing and facilitating assembly of the optical pickup device. It is to provide a composite optical device capable of

[0006]

In order to achieve the above object, an optical pickup device according to the present invention is a composite optical device in which a transparent optical component having a light emitting element, a light receiving element and a partially reflecting surface is provided on a substrate. And a plurality of composite optical devices having different specifications from each other.

Here, typically, the light emitting elements of the plurality of composite optical devices have different emission wavelengths and / or light outputs. Further, typically, in the light emitting element, the light receiving element, and the transparent optical component, the emission optical axis of the light from the light emitting element and the incident optical axis of the light to the light receiving element are substantially coincident with each other on the partially reflecting surface of the transparent optical component. Arranged to do so.

A composite optical device according to the present invention is characterized in that a transparent optical component having a plurality of light emitting elements, a light receiving element and a partially reflecting surface is provided on a substrate, and the plurality of light emitting elements have different specifications from each other. Is.

Here, typically, the plurality of light emitting elements have different emission wavelengths and / or light outputs. In addition, typically, the light emitting element, the light receiving element and the transparent optical component are
The emission optical axis of the light from the light emitting element and the incident optical axis of the light to the light receiving element are arranged so as to substantially coincide with each other on the partially reflecting surface of the transparent optical component.

According to the optical pickup device of the present invention configured as described above, the specifications of the plurality of composite optical devices are designed so as to correspond to a plurality of types of optical discs having different formats from each other. It is possible to write to or read from a plurality of types of optical discs having different formats. Further, since this composite optical device can be made compact, the optical pickup device can be made compact. further,
Since the optical axes of the light emitting element, the light receiving element and the transparent optical component in this composite optical device are adjusted in advance, the optical pickup device can be easily assembled.

According to the composite optical device of the present invention configured as described above, by designing the specifications of the plurality of light emitting elements so as to correspond to a plurality of types of optical discs of different formats, these are mutually It is possible to write to or read from a plurality of types of optical discs having different formats. Further, since this composite optical device can be constructed in a small size, a small optical pickup device can be constructed using this composite optical device. Furthermore, the light-emitting element, the light-receiving element, and the optical axis of the transparent optical component in this composite optical device can be adjusted relatively easily as in a conventional composite optical device equipped with a single light-emitting element. Therefore, it is easy to assemble.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding portions are denoted by the same reference numerals.

For convenience of description of the following embodiments, first, a general laser coupler used in an optical pickup device will be described.

1 and 2 show this laser coupler. Here, FIG. 1 is a perspective view of the laser coupler, and FIG. 2 is a sectional view taken along the longitudinal direction of the laser coupler.
As shown in FIGS. 1 and 2, in this laser coupler, a micro prism 2 made of optical glass is provided on a photodiode IC1, and an LOP (Laser on Photodiode) chip having a semiconductor laser 4 mounted on the photodiode 3 is provided. Are mounted next to each other. Here, the photodiode IC1 is an IC in which a pair of photodiodes PD1 and PD2 for detecting an optical signal, a signal current-voltage conversion amplifier, an arithmetic processing unit, and the like (not shown) are integrated. The photodiode 3 is for monitoring the light output from the rear end surface of the semiconductor laser 4 and controlling the light output from the front end surface thereof. The photodiode 3 is also mounted such that the semiconductor laser 4 is normally mounted so that its junction is on the lower side. Therefore, the laser light emitted from the front end surface of the semiconductor laser 4 is reflected on the surface of the photodiode IC1. The semiconductor laser 4 also has a role of being positioned at a position sufficiently higher than the surface of the photodiode IC1 in order to prevent it from becoming noise light.

As shown in FIG. 2, the micro prism 2
Has an inclined surface 2a serving as a light incident surface, an upper surface 2b, a bottom surface 2c, an end surface 2d and an end surface 2e. Then, a half mirror 5 is provided on the slope 2a, a total reflection film 6 is provided on the upper surface 2b, an antireflection film 7 is provided on the bottom surface 2c, the end surface 2d is configured as a mirror surface, and the end surface 2e is formed by light. An absorption film 8 is provided. To give an example of the size of the micro prism 2, the height is 0.6 mm, the total length is 1.52 mm, and the width is 1.8 m.
m, the length of the upper surface 2b is 1.1 mm.

Silicon dioxide (SiO 2) is further formed on the antireflection film 7 provided on the bottom surface 2 c of the micro prism 2.
₂ ) A membrane (not shown) is provided. On the other hand, a silicon nitride (SiN) film (not shown) is provided on the photodiode PD1 of the photodiode IC1, and a SiO ₂ film 9 is provided so as to cover the surfaces of the SiN film and the photodiode PD2. . Then, the SiO ₂ film provided on the bottom surface 2c of the micro prism 2 is attached to the SiO ₂ film 9 on the photodiode IC1 by the adhesive 10.
And the micro prism 2 is mounted on the photodiode IC1. In this case, the SiN film on the photodiode PD1 and the SiO 2 film on the SiN film
_{The two} films 9 form a half mirror. The SiO ₂ film provided on the antireflection film 7 is for strengthening the adhesive force of the adhesive 10 to the micro prism 2. Further, the SiO ₂ film 9 is a photodiode IC.
In addition to the passivation of the surface of No. 1, the adhesive strength of the microprism 2 by the adhesive 10 is strengthened.

In this case, the photodiodes PD1 and PD2 for detecting an optical signal are of a four-division type. That is, as shown in FIG. 3, the photodiode PD1 has four photodiodes A1 to A4 provided separately from each other, and the photodiode PD2.
Has four photodiodes B1 to B4 provided separately from each other.

The laser coupler configured as described above is
As shown in FIG. 4, it is housed in, for example, a flat package 11 made of ceramics, and is sealed by a window cap (not shown).

Next, the operation of the above laser coupler will be described with reference to FIG. As shown in FIG. 5, in the above laser coupler, the laser light L emitted from the front end surface of the semiconductor laser 4 is reflected by the half mirror (not shown) on the inclined surface 2 a of the micro prism 2. After that, it is condensed by the objective lens OL, and the optical disc D
Incident on. The objective lens OL is provided integrally with or separately from the laser coupler. The laser light L reflected by the optical disc D enters the inside of the micro prism 2 through the half mirror on the slope 2 a of the micro prism 2. Half (50%) of the light that has entered the inside of the micro prism 2 is incident on the photodiode PD1, and the other half (50%) of the light is emitted from the half mirror provided on the photodiode PD1. The photodiode P is sequentially reflected by the upper surface 2b of the micro prism 2.
It is incident on D2.

In this case, when the laser light L is focused on the recording surface of the optical disc D, the photodiode P
The laser beams L on D1 and PD2 are designed to have the same spot size, but when the optical disc D is displaced and the focus position deviates from the recording surface, the laser beams L on these photodiodes PD1 and PD2 are changed. Spot size will be different from each other. Therefore, the focus error signal can be detected by making the difference between the output signal from the photodiode PD1 and the output signal from the photodiode PD2 correspond to the shift of the focus position. And
The zero point of this focus error signal corresponds to the point where the focus position coincides with the recording surface of the optical disc D, that is, the just focus point, and feedback is given to the focus servo system so that this focus error signal becomes zero. In this way, the just focus state is maintained, and recording / reproduction of the optical disc D is performed without any trouble. In FIG. 3, the focus error signal is (A1 + A2 + B3 + B4)-(A3 + A4 + B1).
+ B2).

Now, assuming the above, the first embodiment of the present invention will be described. In the first embodiment, the optical pickup device is configured by using the two laser couplers described above.

FIG. 6 shows an optical pickup device according to the first embodiment of the present invention. As shown in FIG. 6, this first
The optical pickup device according to the embodiment is composed of two laser couplers LC1 and LC2, a half mirror HM, and an objective lens OL. Laser coupler LC1
The LC2 and the LC2 have a configuration as shown in FIGS. 1 and 2, for example. In this case, the laser coupler LC1 is arranged on the common optical axis of the half mirror HM and the objective lens OL. Further, the laser coupler LC2 is arranged at a position where the incident or emitted optical axis of the laser coupler LC2 and the incident or emitted optical axis of the laser coupler LC1 substantially coincide with each other in the half mirror HM. Here, it is preferable to use one having a polarization function as the half mirror HM, and the half mirror HM makes the laser beams from the laser couplers LC1 and LC2 different in polarization from each other to maximize the light utilization efficiency.

In the first embodiment, the laser coupler LC1 is designed to have optimum specifications for recording / reproducing an optical disc of one type having a certain format, and the semiconductor laser 4 emits light. The wavelength and / or light output, the light receiving characteristics of the photodiodes PD1 and PD2, etc. are optimized. On the other hand, laser coupler LC
2 is designed to have optimum specifications for recording / reproducing other types of optical discs having different formats from those described above.
Alternatively, the light output and the light receiving characteristics of the photodiodes PD1 and PD2 are optimized.

Here, to give some specific examples of the semiconductor laser 4, the light output is several mW in the emission wavelength band of 780 nm.
, The light output is several tens of mW in the emission wavelength band of 780 nm
, Red emission (emission wavelength of 635 to 680 nm)
With a light output of several mW, red emission (emission wavelength 635-
680 nm) with a light output of several tens of mW, blue light emission (emission wavelength of about 500 nm) with a light output of several mW, and blue light emission (emission wavelength of about 500 nm) with a light output of several tens mW. Depending on the purpose, one is used.

As described above, the optical pickup device according to the first embodiment has the laser couplers LC1 and LC2 designed to the optimum specifications for recording / reproducing two types of optical discs having different formats. , By using any one of these laser couplers LC1 and LC2 depending on the type of the optical disc to be recorded / reproduced, the formats differ from each other.
It is possible to record / reproduce various types of optical disks. Since the laser couplers LC1 and LC2 can be made compact, the size of the optical pickup device can be made smaller than that in the case where the optical pickup device is made up of two packaged large semiconductor lasers. Can be configured. Further, since the optical axes of the semiconductor laser 4, the photodiodes PD1 and PD2, the microprism 2, etc. in the laser couplers LC1 and LC2 have been adjusted in advance, this optical pickup device is easy to assemble.

FIG. 7 shows a laser coupler according to the second embodiment of the present invention, which is used in an optical pickup device. As shown in FIG. 7, in the laser coupler according to the second embodiment, two laser couplers LC1 and LC2 having the same configurations as those shown in FIGS. 1 and 2 have their optical axes parallel to each other. Are arranged adjacent to each other on the same photodiode IC1. These laser couplers LC1 and LC2
Like in the first embodiment, is designed to have the optimum specifications for recording / reproducing one type of optical disc of a certain format. Here, the LOP chip of the laser coupler LC1 and the laser coupler LC2
The distance between the LOP chip and the LOP chip depends on the mounting accuracy of these LOP chips, but is usually about 500 μm, and can be set to a minimum of 300 to 400 μm.

When an optical pickup device is constructed by using the laser coupler according to the second embodiment, the objective lens may be provided integrally with the laser coupler or may be provided separately. This objective lens is a laser coupler LC1.
And LC2.

According to the second embodiment, the same advantages as those of the first embodiment can be obtained. That is, when the laser coupler according to the second embodiment is used in the optical pickup device, by using either the laser coupler LC1 or LC2 depending on the type of the optical disc to be recorded / reproduced, It is possible to record / reproduce two types of optical discs having different formats.

Further, since the laser couplers LC1 and LC2 are integrated on the same photodiode IC1, the optical pickup device can be constructed in a small size, and only one photodiode IC1 and one package are provided. As a result, the manufacturing cost can be reduced. Furthermore, adjustment of the optical axis when these laser couplers LC1 and LC2 are integrated on the photodiode IC1 is relatively simple, as with the laser couplers shown in FIGS.

FIG. 8 shows a laser coupler according to the third embodiment of the present invention, which is used in an optical pickup device. As shown in FIG. 8, in the laser coupler according to the third embodiment, the microprism 2 of the laser coupler LC1 and the microprism 2 of the laser coupler LC2 are integrally formed. Since the other points are the same as those of the laser coupler according to the second embodiment, description thereof will be omitted.

When an optical pickup device is constructed using the laser coupler according to the third embodiment, the objective lens is provided integrally with or separately from the laser coupler, and the objective lens is shared by the laser couplers LC1 and LC2. What can be done is the same as described in the second embodiment. Also according to the third embodiment, the second
The same advantages as those of the embodiment can be obtained.

FIG. 9 shows a laser coupler according to the fourth embodiment of the present invention, which is used in an optical pickup device. As shown in FIG. 9, in the laser coupler according to the fourth embodiment, the same photodiode I is used.
On C1, two laser couplers LC1 and LC2 are
The photodiodes PD1 and PD2 for detecting an optical signal and the micro prism 2 are shared, and they are integrated so as to face each other and share the optical axis. In this case, the micro-prism 2 has slopes 2a serving as light incident surfaces on the LOP chip side of the laser coupler LC1 and the LOP chip side of the laser coupler LC2, respectively. Other things
Since it is the same as the laser coupler according to the second embodiment,
Description is omitted.

In the fourth embodiment, the laser light L emitted from one semiconductor laser 4 and reflected by one slope 2a of the micro prism 2 and the other semiconductor laser 4 emitted from the other semiconductor laser 4 are used. Slope 2a
The distance from the laser beam L reflected by is typically 1 m.
m.

When an optical pickup device is constructed using the laser coupler according to the fourth embodiment, the objective lens is provided integrally with or separately from the laser coupler, and the objective lens is shared by the laser couplers LC1 and LC2. What can be done is the same as described in the second embodiment.

According to the fourth embodiment, the same advantages as those of the second embodiment can be obtained. In this case, in particular, since the laser couplers LC1 and LC2 share the photodiodes PD1 and PD2 and the microprism 2, the photodiode IC1 can be further downsized, and therefore the optical pickup device can be downsized. Can be converted.

FIG. 10 shows a laser coupler according to the fifth embodiment of the present invention, which is used in an optical pickup device. As shown in FIG. 10, in the laser coupler according to the fifth embodiment, a single LOP chip includes two semiconductor lasers 4 having different emission wavelengths and / or optical outputs. Specifically, a step portion 3a is formed above the photodiode chip 3, and below this step portion 3a, an emission wavelength and / or an optical output that is optimum for writing or reading to or from one type of optical disc of a certain format is read. And the semiconductor laser 4 designed to have an optimum emission wavelength and / or optical output for writing or reading to / from another type of optical disc having a different format is provided above the stepped portion 3a. ing. Here, the height of the step portion 3a is selected sufficiently large so that the laser lights L emitted from the front end faces of the semiconductor lasers 4 do not interfere with each other. Since the other points are the same as those of the laser coupler according to the second embodiment, description thereof will be omitted.

When an optical pickup device is constructed using the laser coupler according to the fifth embodiment, the objective lens is provided integrally with or separately from the laser coupler, and the objective lens is shared by the laser couplers LC1 and LC2. What can be done is the same as described in the second embodiment.

Also in the fifth embodiment, the same advantages as those in the second embodiment can be obtained. In this case, in particular, since the laser couplers LC1 and LC2 share the photodiodes PD1 and PD2, the microprism 2 and the photodiode 3, the photodiode IC1 can be further downsized, and thus the optical pickup device. Can be further miniaturized.

FIG. 11 shows a laser coupler according to the sixth embodiment of the present invention, which is used in an optical pickup device. As shown in FIG. 11, in the laser coupler according to the sixth embodiment, two laser couplers LC1 and LC2 are provided on the same photodiode IC1.
Is a part of the photodiodes PD1, PD2 and PD1 'for detecting the optical signal (in this case, the photodiode PD
2) and the micro-prism 2 are shared, and they are integrated so as to face each other with the optical axis in common. In this case, the laser coupler LC1 includes the photodiodes PD1 and PD.
2 detects the optical signal, and the laser coupler LC2 detects the optical signal using the photodiodes PD1 'and PD2. Since the other points are the same as those of the laser coupler according to the second embodiment, description thereof will be omitted.

When an optical pickup device is constructed using the laser coupler according to the sixth embodiment, the objective lens is provided integrally with or separately from the laser coupler, or the objective lens is shared by the laser couplers LC1 and LC2. What can be done is the same as described in the second embodiment. Also according to this sixth embodiment, the second
The same advantages as those of the embodiment can be obtained.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.

For example, the numerical values and materials mentioned in the above embodiment are merely examples, and different numerical values and materials may be used. Further, in the above-described first embodiment, for example, a polarization beam splitter may be used instead of the half mirror HM, and the objective lens OL may be provided separately from the optical pickup device.

In the fourth embodiment, the laser couplers LC1 and LC2 are the photodiode PD.
1 and PD2 share the micro prism 2,
Laser couplers LC1 and LC2 in the embodiment of
Shares the photodiode PD2 and the micro prism 2, but a pair of photodiodes PD1 and P is provided for each of the laser couplers LC1 and LC2.
D2 may be provided so as to share the optical axis with each other, and these laser couplers LC1 and LC2 may share only the micro prism 2.

Furthermore, in the above-described first to sixth embodiments, two laser couplers LC1 and LC2 are integrated on the same photodiode IC1 to form one laser coupler, but three laser couplers are provided. The above laser couplers may be integrated on the same photodiode IC1 to form one laser coupler.

Note that, as shown in FIG. 12, two laser couplers LC1 and LC2 are laterally arranged in parallel in the same flat package 11 and mounted, and when they are used in an optical pickup device, the above described The same advantages as the embodiment can be obtained. In this case as well, the objective lens can be shared by the laser couplers LC1 and LC2, but considering the lens field of view, it is preferable that these laser couplers LC1 and LC2 be mounted close to each other, for example, to about 100 μm. The laser couplers LC1 and LC2 may be arranged in parallel in the same flat package 11 in the vertical direction. Furthermore, three or more laser couplers may be mounted in the same flat package 11.

[0046]

As described above, according to the optical pickup device of the present invention, since the plurality of composite optical devices have different specifications from each other, writing or reading can be performed on a plurality of types of optical discs having different formats. It is compact, and easy to assemble.

According to the composite optical device of the present invention, the specifications of the plurality of light emitting elements are different from each other. Therefore, when the composite optical device is used in an optical pickup device, writing or reading is performed on a plurality of types of optical discs having different formats. The optical pickup device can be downsized and the assembling can be facilitated.

[Brief description of drawings]

FIG. 1 is a perspective view showing a general laser coupler used in an optical pickup device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a general laser coupler used in the optical pickup device according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a pattern of a photodiode for detecting an optical signal in the laser coupler shown in FIGS. 1 and 2.

FIG. 4 is a perspective view showing a laser coupler packaged in a flat package.

FIG. 5 is a schematic diagram for explaining an operation when a laser coupler is applied to an optical pickup device.

FIG. 6 is a schematic diagram showing a laser coupler according to the first embodiment of the present invention.

FIG. 7 is a perspective view showing a laser coupler according to a second embodiment of the present invention.

FIG. 8 is a perspective view showing a laser coupler according to a third embodiment of the present invention.

FIG. 9 is a perspective view showing a laser coupler according to a fourth embodiment of the present invention.

FIG. 10 is a perspective view showing a laser coupler according to a fifth embodiment of the present invention.

FIG. 11 is a perspective view showing a laser coupler according to a sixth embodiment of the present invention.

FIG. 12 is a perspective view showing a laser coupler according to another embodiment of the present invention.

[Explanation of symbols]

1 ... Photodiode IC, 2 ... Microprism, 4 ... Semiconductor laser, PD1, PD1 ', PD
2 ... Photodiode, LC1, LC2 ... Laser coupler

Claims (13)

[Claims] 1. A plurality of composite optical devices, each of which has a light-emitting element, a light-receiving element, and a transparent optical component having a partially reflecting surface provided on a substrate, and the specifications of the plurality of composite optical devices are different from each other. Optical pickup device. 2. The optical pickup device according to claim 1, wherein the light emitting elements of the plurality of composite optical devices have emission wavelengths and / or optical outputs different from each other. 3. The light-emitting element, the light-receiving element and the transparent optical component are such that the emission optical axis of light from the light-emitting element and the incident optical axis of light to the light-receiving element are the partial reflection of the transparent optical component. 2. The optical pickup device according to claim 1, wherein the optical pickup devices are arranged so that their surfaces substantially coincide with each other. 4. The light according to claim 1, wherein the base is a semiconductor substrate, the light emitting element is a semiconductor laser, the light receiving element is a photodiode, and the transparent optical component is a prism. Pickup device. 5. A composite optical device, wherein a transparent optical component having a plurality of light emitting elements, a light receiving element and a partially reflecting surface is provided on a substrate, and the plurality of light emitting elements have different specifications from each other. 6. The plurality of light emitting elements have an emission wavelength and / or
Alternatively, the light outputs are different from each other.
The composite optical device described. 7. The light emitting element, the light receiving element, and the transparent optical component are such that the emission optical axis of light from the light emitting element and the incident optical axis of light to the light receiving element are the partial reflection of the transparent optical component. The compound optical device according to claim 5, wherein the compound optical devices are arranged so as to be substantially coincident with each other in a plane. 8. The plurality of light emitting elements are arranged adjacent to each other so that their optical axes are substantially parallel to each other, and the transparent optical component is provided corresponding to each of the plurality of light emitting elements. The composite optical device according to claim 5, wherein: 9. The plurality of light emitting elements are arranged adjacent to each other such that their optical axes are substantially parallel to each other, and the transparent optical component is a single transparent optical component common to the plurality of light emitting elements. The composite optical device according to claim 5, wherein the composite optical device is provided. 10. The composite optical apparatus according to claim 5, wherein the plurality of light emitting elements share an optical axis with each other and the light receiving elements are also shared. 11. The composite optical device according to claim 5, wherein the plurality of light emitting elements are arranged at positions different in height from the surface of the base. 12. The composite optical apparatus according to claim 5, wherein the plurality of light emitting elements are arranged so as to share an optical axis with each other and share a part of the light receiving element. 13. The composite according to claim 5, wherein the substrate is a semiconductor substrate, the light emitting element is a semiconductor laser, the light receiving element is a photodiode, and the transparent optical component is a prism. Optical device.